PID controller design for fractional-order systems with time delays

Classical proper PID controllers are designed for linear time invariant plants whose transfer functions are rational functions of sα, where 0<α<1, and s is the Laplace transform variable. Effect of inputoutput time delay on the range of allowable controller parameters is investigated. The allowable PID controller parameters are determined from a small gain type of argument used earlier for finite dimensional plants. © 2011 Elsevier B.V. All rights reserved